Numerous reproductive pathologies can be attributed to neural integration of environmental and social information: The purpose of this study is to determine how reproduction is influenced by neural transduction of social cues. Specifically, this study aims to identify the neural pathways by which male birdsong stimulates in females the secretion of gonadotropin releasing hormone (GnRH), a hypothalamic hormone essential for gonadal maturation and reproductive behavior. Wild-caught European starlings (Sturnus vulgaris), a songbird in which females are reproductively stimulated by male song, will be used as a model system. The strategy will be to localize the expression of immediate early genes (IEG) via immunocytochemistry and to compare IEG expression in controls to that in females exposed to conspecific song. The timecourse of IEG expression will be investigated by sacrificing females at various times following song stimulation with the prediction that eventually the stimulus will cause enhanced IEG expression in GnRH neurons when compared to controls. Colocalization of song-induced EEG and GnRH would suggest a role for song in the stimulation of the reproductive axis. These experiments will be followed with additional studies aimed at determining whether the neural regions showing IEG expression as a result of starling song are necessary for EEG expression in downstream regions. This will be accomplished by selectively lesioning regions showing EEG expression and determining whether such lesions reduce EEG expression in brain regions downstream from the lesion. The proposed research should give insight into the neural mechanisms by which environmental variation in general and social input in particular influence the development of reproductive processes. Such knowledge is essential for a thorough understanding of numerous behavioral and reproductive pathologies